Effect of Plant Density and Ethephon Spraying on some Growth Traits of the Sunflower (Helianthus aannus L.) (Shamos variety)

Abstract

The field experiment was carried out during the spring season (2023), to study the effect of plant density, spraying with ethephon, and their interaction on the growth of sunflower (Shamous variety). The experiment was applied using a randomized complete block design (R.C.B.D), according to the split plot design with three replicates. The main plots included four levels of ethephon (0, 600, 1200, and 1800 ppm), which has the symbol E0, E1, E2 and E3 respectively. The Sub Plot included four planting distances (20, 30, 40, and 50 cm) among plants, which were symbolized as D1, D2, D3, and D4, respectively. The results showed a significant effect among planting distances, the distance of 20 cm between plants in D1 achieved the highest average plant height (209.33 cm) and the area index (3.70), while D4, was the highest average leaf area (8990.08 cm2) and the leaves number (30.70 leaves plant-1). The level of ethephon E3, was a high average of leaves No. (28.80 leaves plant-1), the leaf area (7394.66 cm2), and leaf area index (2.95), while the E0 level gave the highest average for plant height (203.25 cm).